Before the emergence of ultra-wideband (UWB) radios, widely used wireless communications were based on sinusoidal carriers, and impulse technologies were employed only in specific applications (e.g. radar). In 2002, the Federal Communication Commission (FCC) allowed unlicensed operation between 3.1–10.6 GHz for UWB communication, using a wideband signal format with a low EIRP level (−41.3dBm/MHz). UWB communication systems then emerged as an alternative to narrowband systems and significant effort in this area has been invested at the regulatory, commercial, and research levels.

IEEE Transactions on Microwave Theory and Techniques and Antennas and Propagation Announce a Joint Special Issue on Ultra-Wideband (UWB) Technology

This paper presents a comparative overview of the most important approaches presented to address the behavioral modeling of microwave and wireless power amplifiers (PAs). Starting from a theoretical framework of recursive and nonrecursive nonlinear filters, it proposes a classification of the various PA behavioral models, discussing their abilities to represent the different effects observed in practical circuits. Using that formal procedure, one explains how it was possible to integrate a wide range of behavioral modeling activities and to show that some of them, which at first glance seemed to be quite different, are, indeed, identical in their modeling capabilities.

A comparative overview of microwave and wireless power-amplifier behavioral modeling approaches

A new representation of the Volterra series is proposed, which is derived from a previously introduced modified Volterra series, but adapted to the discrete time domain and reformulated in a novel way. Based on this representation, an efficient model-pruning approach, called dynamic deviation reduction, is introduced to simplify the structure of Volterra-series-based RF power amplifier behavioral models aimed at significantly reducing the complexity of the model, but without incurring loss of model fidelity. Both static nonlinearities and different orders of dynamic behavior can be separately identified and the proposed representation retains the important property of linearity with respect to series coefficients. This model can, therefore, be easily extracted directly from the measured time domain of input and output samples of an amplifier by employing simple linear system identification algorithms. A systematic mathematical derivation is presented, together with validation of the proposed method using both computer simulation and experiment

/pdf/dynamic-deviation-reduction-based-volterra-behavioral-41zmefptaa.pdf

Dynamic Deviation Reduction-Based Volterra Behavioral Modeling of RF Power Amplifiers

Preface. About the Authors. Acknowledgments. 1 Power Amplifier Fundamentals. 1.1 Introduction. 1.2 Definition of Power Amplifier Parameters. 1.3 Distortion Parameters. 1.4 Power Match Condition. 1.5 Class of Operation. 1.6 Overview of Semiconductors for PAs. 1.7 Devices for PA. 1.8 Appendix: Demonstration of Useful Relationships. 1.9 References. 2 Power Amplifier Design. 2.1 Introduction. 2.2 Design Flow. 2.3 Simplified Approaches. 2.4 The Tuned Load Amplifier. 2.5 Sample Design of a Tuned Load PA. 2.6 References. 3 Nonlinear Analysis for Power Amplifiers. 3.1 Introduction. 3.2 Linear vs. Nonlinear Circuits. 3.3 Time Domain Integration. 3.4 Example. 3.5 Solution by Series Expansion. 3.6 The Volterra Series. 3.7 The Fourier Series. 3.8 The Harmonic Balance. 3.9 Envelope Analysis. 3.10 Spectral Balance. 3.11 Large Signal Stability Issue. 3.12 References. 4 Load Pull. 4.1 Introduction. 4.2 Passive Source/Load Pull Measurement Systems. 4.3 Active Source/Load Pull Measurement Systems. 4.4 Measurement Test-sets. 4.5 Advanced Load Pull Measurements. 4.6 Source/Load Pull Characterization. 4.7 Determination of Optimum Load Condition. 4.8 Appendix: Construction of Simplified Load Pull Contours through Linear Simulations. 4.9 References. 5 High Efficiency PA Design Theory. 5.1 Introduction. 5.2 Power Balance in a PA. 5.3 Ideal Approaches. 5.4 High Frequency Harmonic Tuning Approaches. 5.5 High Frequency Third Harmonic Tuned (Class F). 5.6 High Frequency Second Harmonic Tuned. 5.7 High Frequency Second and Third Harmonic Tuned. 5.8 Design by Harmonic Tuning. 5.9 Final Remarks. 5.10 References. 6 Switched Amplifiers. 6.1 Introduction. 6.2 The Ideal Class E Amplifier. 6.3 Class E Behavioural Analysis. 6.4 Low Frequency Class E Amplifier Design. 6.5 Class E Amplifier Design with 50# Duty-cycle. 6.6 Examples of High Frequency Class E Amplifiers. 6.7 Class E vs. Harmonic Tuned. 6.8 Class E Final Remarks. 6.9 Appendix: Demonstration of Useful Relationships. 6.10 References. 7 High Frequency Class F Power Amplifiers. 7.1 Introduction. 7.2 Class F Description Based on Voltage Wave-shaping. 7.3 High Frequency Class F Amplifiers. 7.4 Bias Level Selection. 7.5 Class F Output Matching Network Design. 7.6 Class F Design Examples. 7.7 References. 8 High Frequency Harmonic Tuned Power Amplifiers. 8.1 Introduction. 8.2 Theory of Harmonic Tuned PA Design. 8.3 Input Device Nonlinear Phenomena: Theoretical Analysis. 8.4 Input Device Nonlinear Phenomena: Experimental Results. 8.5 Output Device Nonlinear Phenomena. 8.6 Design of a Second HT Power Amplifier. 8.7 Design of a Second and Third HT Power Amplifier. 8.8 Example of 2nd HT GaN PA. 8.9 Final Remarks. 8.10 References. 9 High Linearity in Efficient Power Amplifiers. 9.1 Introduction. 9.2 Systems Classification. 9.3 Linearity Issue. 9.4 Bias Point Influence on IMD. 9.5 Harmonic Loading Effects on IMD. 9.6 Appendix: Volterra Analysis Example. 9.7 References. 10 Power Combining. 10.1 Introduction. 10.2 Device Scaling Properties. 10.3 Power Budget. 10.4 Power Combiner Classification. 10.5 The T-junction Power Divider. 10.6 Wilkinson Combiner. 10.7 The Quadrature (90 ) Hybrid. 10.8 The 180 Hybrid (Ring Coupler or Rat-race). 10.9 Bus-bar Combiner. 10.10 Other Planar Combiners. 10.11 Corporate Combiners. 10.12 Resonating Planar Combiners. 10.13 Graceful Degradation. 10.14 Matching Properties of Combined PAs. 10.15 Unbalance Issue in Hybrid Combiners. 10.16 Appendix: Basic Properties of Three-port Networks. 10.17 References. 11 The Doherty Power Amplifier. 11.1 Introduction. 11.2 Doherty's Idea. 11.3 The Classical Doherty Configuration. 11.4 The 'AB-C' Doherty Amplifier Analysis. 11.5 Power Splitter Sizing. 11.6 Evaluation of the Gain in a Doherty Amplifier. 11.7 Design Example. 11.8 Advanced Solutions. 11.9 References. Index.

/pdf/high-efficiency-rf-and-microwave-solid-state-power-4xdx1261hq.pdf

High Efficiency RF and Microwave Solid State Power Amplifiers

A comparative study of state-of-the-art behavioral models for microwave power amplifiers (PAs) is presented in this paper. After establishing a proper definition for accuracy and complexity for PA behavioral models, a short description on various behavioral models is presented. The main focus of this paper is on the modeling accuracy as a function of computational complexity. Data is collected from measurements on two PAs-a general-purpose amplifier and a Doherty PA designed for WiMAX-for different output power levels. The models are characterized in terms of accuracy and complexity for both in-band and out-of-band error. The results show that, among the models studied, the generalized memory polynomial behavioral model has the best tradeoff for accuracy versus complexity for both PAs, and can obtain high performance at half of the computational cost of all other models analyzed.

https://publications.lib.chalmers.se/records/fulltext/local_121905.pdf

A Comparative Analysis of the Complexity/Accuracy Tradeoff in Power Amplifier Behavioral Models

A technology-independent, non-quasi-static non-linear model of electron devices capable of accurate predictions at microwave and millimetre waves is proposed in this paper. The model is based on the definition of a quasi-static associated device, which is controlled by means of equivalent voltages. In particular, in the paper it is shown how to define and experimentally identify suitable voltage-controlled voltage sources, which modify the original domain of applied voltages and create a suitable control environment for the purely-quasi-static associated device. The advantage of this approach is that conventional purely quasi-static models can still be adopted even at very high frequencies, if suitable equivalent voltages are applied. Preliminary experimental validation of the approach is provided in the paper by means of a GaAs PHEMT.

A simple non-quasi-static non-linear model of electron devices

A mathematical approach, which has been recently proposed for the nonlinear modelling of microwave transistors, is adopted for the large-signal performance prediction of Dual-Gate GaAs MESFETs in the framework of Harmonic-Balance circuit analysis. Unlike classical equivalent circuits, the nonlinear model adopted here can be directly identifled on the bases of DC characteristics and small-signal biasdependent AC parameters without need for optimisation-based procedures for parameter extraction. The validity of the large-signal modelling approach is confirmed by accurate physics-based numerical simulations of a Dual-Gate GaAs MESFET mixer.

Large-signal modelling of Dual-Gate GaAs MESFETs

In this paper, a new approach to class-A power amplifier design is proposed. Such a technique, which is mostly based on low-frequency characterisation, allows to reach the same design goals obtained through expensive nonlinear setups operating at microwave frequencies. In order to demonstrate the effectiveness of the proposed design technique, a practical example of class-A power amplifier design, based on GaN technology, is deeply investigated.

Class-A power amplifier design technique based on electron device low-frequency characterization

Recently proposed,general-purpose mathematical approaches,such as the Finite Memory Model (FMM)[6 ]and the Non-linear Discrete Convolution Model (NDC)[7 ],are used for the nonlinear modeling of electron devices. Both models derive from the same theoretical approach and are identi ﬁed on the basis of conventional DC (and/or pulsed characteristics)and small-signal differential parameter measurements. The implementation of the two models in the framework of the Agilent-ADS CAD package is described in the paper and a wide experimental validation,including small-and large-signal results,is presented for GaAs- MESFET,and PHEMT devices.

FMM and NDC technology-independent finite-memory nonlinear device models: ADS implementation and large-signal validation results

Electron device modeling is a challenging task at millimeter frequencies. Conventional approaches based on lumped equivalent circuits become inappropriate to describe possible complex distributed effects, which may strongly affect the electrical transistor performance. Moreover, standard network analyzers do not allow for low-cost device characterization solutions at very high frequencies. In the paper it is shown how an empirical, scalable distributed model based on standard S-parameter measurements up to 50 GHz can be efficiently exploited to obtain very accurate small-signal predictions up to 110 GHz. Experimental validation is presented for Philips 0.2 /spl mu/m PHEMT devices. Practical consideration on the best criteria for model extraction are also provided in the paper.

http://ieeexplore.ieee.org/iel5/6946/18681/00861797.pdf

Giorgio Vannini

Papers

A simple non-quasi-static non-linear model of electron devices

Large-signal modelling of Dual-Gate GaAs MESFETs

Class-A power amplifier design technique based on electron device low-frequency characterization

FMM and NDC technology-independent finite-memory nonlinear device models: ADS implementation and large-signal validation results

A 110 GHz scalable FET model based on 50 GHz S-parameter measurements